The Chemical Elements

All materials, whether solid, liquid or gas, are made of atoms. Atoms are the smallest
bits of matter. Scientists have found over 100 different kinds of atoms. The many
different materials we encounter are made from combinations of these atoms. A material in
which all atoms are the same kind is called an element. Therefore, there are over 100
different elements.

Each element has been assigned a number, called its atomic number. In the Chem Time
clock, the numbers have been replaced by the symbols of the corresponding element.

Atomic Number

Symbol

Element

1

H

hydrogen

Hydrogen is the lightest and the most common atom in the universe.

2

He

helium

Helium was first discovered in the sun, and its name comes from the
ancient Greek word for sun.

3

Li

lithium

Lithium is the lightest metal, so light it floats on water (and it reacts
with water, too).

4

Be

beryllium

Beryllium is a component of the gemstones beryl, emerald, and aquamarine.

5

B

boron

Boron is found in borax, which is a commonly used water softener in
laundry detergents.

6

C

carbon

Both diamond and graphite are pure carbon, and so are the
newly-discovered buckyballs.

7

N

nitrogen

Nitrogen is the major component of air.

8

O

oxygen

Oxygen is the second most abundant element on earth (after silicon).

9

F

fluorine

Fluorine is used in making fluoride toothpaste.

10

Ne

neon

Neon is a gas that glows red-orange when electricity flows through it in
neon signs.

11

Na

sodium

Sodium is one of the two elements in table salt (the other is chlorine).

12

Mg

magnesium

Magnesium is a light metal, and its alloys are used in
"mag" wheels on sports cars.

13

Al

aluminum

Aluminum metal reacts with oxygen, but it forms an oxide
coating protects it from further reaction.

14

Si

silicon

Silicon is the most abundant element in the earth's
surface; it's used in making electronic semiconductors.

15

P

phosphorus

Phosphorus is a non-metal and essential in all biological
organisms.

16

S

sulfur

Sulfur is a yellow solid, and its chief industrial compound is
sulfuric acid.

17

Cl

chlorine

Chlorine is a green gas, but dissolved in water it is an
effective disinfectant.

18

Ar

argon

Argon is an unreactive gas, and it is used to fill light
bulbs so the hot filament does not burn.

19

K

potassium

Potassium is a metal that reacts with water, and its
compounds are essential to living organisms.

20

Ca

calcium

Calcium is a metal, and it is an essential component of
bones and teeth.

21

Sc

scandium

Scandium is a very rare element, and so it is quite
expensive and has few uses.

22

Ti

titanium

Titanium is a metal, and titanium dioxide is the white
pigment used in most paints.

23

V

vanadium

Vanadium is a metal that is added to steel to make it
stronger and more heat resistant.

24

Cr

chromium

Chromium is a metal whose compounds come in many colors, which is the reason
for the element's name.